A group of conservative congressmen, bolstered by an unusually heavy lobbying campaign by the Moral Majority, intend to force floor votes in both houses of Congress today on resolutions to overturn the District of Columbia's new act regulating sexual practices.

D.C. officials and local citizen groups have warned that the resolutions pose the greatest threat yet to self-government in the city because they seek to strike down an exclusively local act, an action the full Congress has never before taken during the city's seven-year experience with limited home rule.

But the efforts of the Moral Majority, which has sent out several hundred thousand mass mailing "alerts" to members around the country, may be having some impact in favor of the resolutions, congressional staffers said yesterday.

A spokesman for the Citizens for Home Rule, a coalition of local groups working against the resolutions, said the vote "looks very tight" in both houses.

The Moral Majority lobbying effort intensified yesterday as a leader of the Lynchburg, Va.-based organization called the resolutions the group's top priority in Congress and threatened members with political consequences if they fail to support them.

"The District's sex act is what I term a perverted act about perverted acts," Dr. Ronald Godwin, the Moral Majority's vice president, told the Senate D.C. subcommittee yesterday. "Make no mistake, a vote against the resolutions is a vote for sodomy, bestiality, fornication, adultery and seduction of a student by a teacher."

The subcommittee, chaired by Sen. Charles McC. Mathias (R-Md.), conducted a 2 1/2-hour hearing on the resolutions yesterday, but adjourned without taking a vote. The House District Committee voted last week against the resolution, but supporters of the resolution in the House say they will attempt to discharge the measure from the committee so the full House can vote today.

Godwin, who said the Moral Majority had plotted its lobbying strategy against the D.C. law at an annual "summit conference" in the Bahamas last week, said later that the conservative organization intends to monitor closely how congressmen vote. "We intend to let their constituents know what their elected representatives do on this one," he said.

Not all conservative organizations have supported the Moral Majority, however. John T. Dolan, director of the National Conservative Political Action Committee and a "New Right" leader, has broken publicly with the Moral Majority and urged that the sex assault law be sustained. Members of Citizens for Home Rule have recently distributed copies of a newspaper article quoting Sen. Barry Goldwater (R-Ariz.) blasting the tactics of "political preachers" and "every religious group that thinks it has some God-granted right to control my vote."

The Moral Majority's tactics also were attacked at yesterday's hearing by City Council member David Clarke (D-Ward 1), the chairman of the council's Judiciary Committee and chief author of the sexual assault act. He noted that most of the states in the country have provisions similar to those in the D.C. act that supporters of the resolution have attacked.

For example, the Moral Majority has criticized the D.C. act because it repeals statutes prohibiting adultery, fornication and sodomy among consenting adults. But Clarke said that 40 states have no criminal penalties against fornication and 25 states have no criminal penalties against adultery or sodomy.

"The Moral Majority seems to think that any point of view other than its own is a sin," said Clarke. "I haven't seen where Dr. Jerry Falwell president of Moral Majority has gone to states where they have similar laws and asked that they be changed."

The act, which at one time contained a provision changing the city's age of consent for sexual relations, also would stiffen penalties for forced sexual offenses.

The resolutions to overturn the act are expected to be brought up today by Rep. Phil Crane (R-Ill.) in the House and Sen. Jeremiah Denton (R-Ala.) in the Senate. Under the 1973 home rule act, Congress can overturn any law passed by the City Council and signed by the mayor with a majority vote of both houses, although laws dealing with the criminal code, such as the sexual assault act, only require a majority vote in either house for disapproval.